The objectives of maximizing snow skier safety must be balanced with the requirements of keeping the skier attached to his or her skis in varying conditions. These objectives have received a great deal of engineering and commercial attention in the past thirty years but increasing the safety of he skier remains an objective.
Failure of the skier to release during falls may result in bone fractures, particularly to the legs, while unexpected release during controlled skiing can be equally injurious. A system to safely release the skier must not only reliably release at specified forces and directions, but must also, to be commercially practical, be adjustable to account for skier ability, equipment variations and environment. Further, the system must be durable and reliably operable over a wide range of temperature and moisture conditions.
Skiers can experience different types of leg injury causing falls during skiing. One type is rapid deceleration when skis strike an object directly ahead of the skier. The object could be quite small, allowing the skier to easily travel over it, if released from the immobilized skis. Unless the boot is cushioned and immediately released allowing the heel to rotate upward as well as releasing the toe, major leg injury can result in an otherwise non-injury accident. A second type is a lateral twisting which can occur when the long edge of a ski catches, that is, fails to track during turns. Unless the boot is cushioned and immediately released allowing the toe and heel to rotate in the plane of the ground surface, serious leg injury can result in an otherwise non-injury accident. In divergent and other types of falls, the skis may get caught in deep snow or other obstructions where a ski is not parallel to the ground surface. The skier may also fall in different directions during turns or other maneuvers. Release of the ski boot must allow rotation and release in planes other than the parallel and perpendicular to the ground surface in order to avoid leg injury. At the same time, ski bindings must also not prematurely release the skis during controlled, but severe, maneuvers which exert different forces, but in similar directions to those where immediate release is required.
Existing products have tended towards greater complexity in order to particularly address the issues of specific release angles and adjustability. An example of this complexity is a patent from Switzerland, No. 574,838 by Besson which requires a sole plate, sole plate attachment to ski boots, two contoured face plates, a face plate mounting block, plungers, and related adjusting mechanisms and ski attachment hardware in order to obtain the direction specific force release features. In another example, U.S. Pat. No. 3,781,028 by Gertsch et al. and U.S. Pat. No. 3,902,729 by Druss are examples of multiple plungers/release points to obtain different release forces in different directions. As the engineering ability to address this wider range of conditions has increased the complexity and number of moving parts, a potential for decreased reliability is presented because of the opportunity for water/ice intrusion into these mechanisms, changing the operating characteristics or even preventing operation entirely.
Another approach has been to compromise safety to gain other advantages. For example, in order to permit step-in access to the binding, the heel attachment of commercial bindings has tended to be less adaptable (the design more compromised)) to the required range and directions of release angles and more attention has been given to the range of release angles of the toepiece. The result is that such bindings may not release in response to a rotational force emanating from heel towards the toe. Similarly, some bindings have not released in straight forward falls and angled upward falls because the release directions of the binding have not been continuous, but oriented in specific directions by the constraints of the moving parts of the system. For instance, almost all bindings are designed to easily release (in a horizontal plane 90 degrees from the vertical) by such mechanisms as horizontally swiveling toepieces, but those bindings will not as easily or reliably release at a release force angle of say 75 degrees unless a separate rotational mechanism is incorporated in the toepiece to move through that angle. In other words, few bindings have yet been made that can operate over the entire continuous 180 degree range of release angles both from toe and heel restraining points, and none that enable continuous or periodic adjustment of the release forces throughout the range.
Thus it is an objective of the within invention to provide a ski binding system that can be configured to release at any predetermined unidirectional force or release angle over a continuous range of forces and angles.
A further objective of the within invention is to provide a ski binding system that will release in response to rotational forces that do not trigger a release within existing systems.
Another objective of the within invention is to accommodate to the continuous range of release specifications while reliably retaining the skier in the binding in all conditions except during falls.
Further objective of the within invention is to provide a greatly simplified ski binding system with a minimum of moving parts in order that reliability and watertight integrity can be maximized.
Another objective of the within invention is to provide a ski binding system that can be easily adjusted or modified to accommodate the specific release requirements of individual skiers of all abilities.
Another objective of the within invention is to provide a ski binding system that can withstand and absorb normal shocks and transient loadings without release and also cushion the transmission of these loadings to the skier.
Finally, it is an objective of the within invention to provide a system that will not be limited to discrete or separated operating angles of release, but provide continuous release capability over the entire range of angles and forces which a ski binding system addresses.
The within invention claims particularly a plunger and socket or receiving groove attachment mechanism with a precisely machined socket or groove contoured to enable release of the plunger mechanism at specified forces and angles. The closest reference in the art known to the applicant is Gertsch U.S. Pat. No. 3,781,028, Safety Ski Binding. Gertsch is limited however, in several ways that the within device is not; specifically Gertsch uses a socket providing for equal release forces at all angles of incidence between retaining pin and boot. Further this device specifies a separate metal plate to hold the socket which plate then must be externally attached to the boot, and a four-point locking pin system is specified or two points on either end of the boot. By contrast the within invention uses either a socket or groove selectively shaped and contoured in a non-uniform fashion so as to provide unequal release forces at different angles of incidence of pin to boot, and provides that the socket or groove may be integral with the boot sole, a preferred configuration as it decreases by 1 degree the freedom of motion between the skier and the ski. Also the within invention can be configured to operate with any number of retaining pins that might be desired to tailor the response to release forces although a 3 point fixation system is considered to be the preferred embodiment because fewer may permit unstable roll moments while more may inhibit free boot movement out of the binding during forward twisting falls. Other similarly limited systems in the art include Ramillon U.S. Pat. No. 3,936,065 and Salmon, on U.S. Pat. No. 4,003,587, both of which require more moving parts and are limited in responsiveness and adjustability. Further, the use of the groove permits shock absorption action of the boot on the binding which the socket mode does not permit. This shock absorption action cushions and prevents injury to the skier, as well as allows bindings to absorb normal loadings without release.
Besson (Switzerland Patent No. 574,838) shows a ski binding system which allows specific release forces in several different directions, however, combinations of forces or forces out of the specific directions provided for are not addressed. More importantly, a disadvantangeous mechanical complexity of multiple components is required. Further disadvantages from this complexity and multiplicity occur from a doubling of releasable attachment equipment (a first attachment of ski boot to boot plate and a second attachment of boot plate to ski occurs). Additionally, the location of the contoured plates does not allow variations in skier heel to toe loadings. Moreover, this plate forces a fixed relationship between release forces at the heel and toe. Finally, the ability to walk on the boot plate is limited.